Voltage-dependent K+ channels play an important role in controlling neuronal activity. There are many types of K+ channels, as revealed by gene cloning techniques. Recently the gene for a mammalian Shaw K+ channel, Kv3.1alpha has been cloned and high levels of Kv3.1alpha mRNA were found in the cochlear nucleus as well as in the neurons in auditory pathways in rats. Although Kv3.1alpha was shown to be expressed at very high levels in auditory neurons, little is known about the physiological role of this channel. The deduced amino acid sequence of Kv3.1alpha shows that there are potential sites for phosphorylation by protein kinase C. Protein phosphorylation has been implicated in the modulation of K+ channels. Investigation of the mechanisms that modulate Kv3.1alpha may help to clarify the role of Kv3.1alpha. Therefore, these experiments are proposed to characterize electrophysiological properties (voltage dependence of gating, kinetics of activation and inactivation, ion selectivity, and pharmacological sensitivity to K+-channel blockers) of Kv3.1alpha in 3T3 fibroblasts transfected with Kv3.1alpha mRNA and in isolated neurons from the cochlear nucleus and the inferior colliculous using voltage-clamp recordings. In addition, to investigate the mechanisms for the modulation of Kv3.1alpha channel by protein phosphorylation, Kv3.1alpha current will be measured after treatment with phorbor ester, an activator of protein kinase C in transfected cells and in the auditory neurons. Electrophysiologial and molecular biological studies of Kv3.1alpha channel and its modulation by protein kinase C are helpful for understanding the physiological control of neuronal excitability and are critical for a complete understanding of an involvement of K+ channels in many neurological disorders.